Backdoor.Berbew.E

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Discovered: June 09, 2004
Updated: February 13, 2007 12:24:13 PM
Type: Trojan Horse
Systems Affected: Windows


Backdoor.Berbew.E is a backdoor Trojan horse that gives an attacker access to your computer. The Trojan opens TCP ports 23232 and 32121, by default.

This Trojan is packed with MPPEC.

Antivirus Protection Dates

  • Initial Rapid Release version June 09, 2004
  • Latest Rapid Release version September 28, 2010 revision 054
  • Initial Daily Certified version June 09, 2004
  • Latest Daily Certified version September 28, 2010 revision 036
  • Initial Weekly Certified release date June 09, 2004

Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

Writeup By: Fergal Ladley

Discovered: June 09, 2004
Updated: February 13, 2007 12:24:13 PM
Type: Trojan Horse
Systems Affected: Windows


When Backdoor.Berbew.E is run, it does the following:

  1. Creates a copy of itself as %System%\<8 random characters>.exe.


    Note: %System% is a variable. The Trojan locates the System folder and copies itself to that location. By default, this is C:\Windows\System (Windows 95/98/Me), C:\Winnt\System32 (Windows NT/2000), or C:\Windows\System32 (Windows XP).

  2. Creates the file, %System%\<8 random characters>.dll.

  3. Creates several files in the %Temp% folder named <8 random characters>.htm. These file names are used as parameters when the Trojan accesses a predefined remote system.

  4. Sets these registry keys to the following:


    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\
    Autocomplete\"AutoSuggest" = "yes"
    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\0\"1601" = "0"
    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\1\"1601" = "0"
    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\2\"1601" = "0"
    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\3\"1601" = "0"
    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\4\"1601" = "0"
    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\5\"1601" = "0"
    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\"GlobalUserOffline" = "0"
    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\
    BrowseNewProcess\"BrowseNewProcess = "yes"
    HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main\"Use FormSuggest" = "yes"
    HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main\"FormSuggest Passwords" = "yes"
    HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main\"FormSuggest PW Ask" = "yes"
    HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main\"Start Page" = "http: //128.121.180.88"
    HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main\"Search Page" = "http: //128.121.180.88"


    These settings will affect a number of Microsoft Internet Explorer settings, such as the home page.

  5. Runs a command shell on TCP port 23232 so that an attacker can gain access by connecting to this port.

  6. Runs an FTP server on TCP port 32121 and opens two randomly selected TCP ports.

  7. Allows an attacker to do any of the following:
    • Restart or shut down the infected system
    • View a list of running processes
    • Stop processes
    • View a log of system information
    • Download and execute a file from a specified Internet address
    • Steal cached passwords


Recommendations

Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

  • Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
  • Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
  • Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
  • Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
  • Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
  • Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
  • If a threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
  • Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services.
  • Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
  • Isolate compromised computers quickly to prevent threats from spreading further. Perform a forensic analysis and restore the computers using trusted media.
  • Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.
  • If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
  • For further information on the terms used in this document, please refer to the Security Response glossary.

Writeup By: Fergal Ladley

Discovered: June 09, 2004
Updated: February 13, 2007 12:24:13 PM
Type: Trojan Horse
Systems Affected: Windows


The following instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

  1. Disable System Restore (Windows Me/XP).
  2. Update the virus definitions.
  3. Run a full system scan and delete all the files detected as Backdoor.Berbew.E.
  4. Reset the Internet Explorer home page.
  5. Reset the Internet Explorer search page.
  6. Check other Internet Explorer settings.

For specific details on each of these steps, read the following instructions.

1. To disable System Restore (Windows Me/XP)
If you are running Windows Me or Windows XP, we recommend that you temporarily turn off System Restore. Windows Me/XP uses this feature, which is enabled by default, to restore the files on your computer in case they become damaged. If a virus, worm, or Trojan infects a computer, System Restore may back up the virus, worm, or Trojan on the computer.

Windows prevents outside programs, including antivirus programs, from modifying System Restore. Therefore, antivirus programs or tools cannot remove threats in the System Restore folder. As a result, System Restore has the potential of restoring an infected file on your computer, even after you have cleaned the infected files from all the other locations.

Also, a virus scan may detect a threat in the System Restore folder even though you have removed the threat.

For instructions on how to turn off System Restore, read your Windows documentation, or one of the following articles:

Note: When you are completely finished with the removal procedure and are satisfied that the threat has been removed, re-enable System Restore by following the instructions in the aforementioned documents.

For additional information, and an alternative to disabling Windows Me System Restore, see the Microsoft Knowledge Base article, "Antivirus Tools Cannot Clean Infected Files in the _Restore Folder ," Article ID: Q263455.

2. To update the virus definitions
Symantec Security Response fully tests all the virus definitions for quality assurance before they are posted to our servers. There are two ways to obtain the most recent virus definitions:
  • Running LiveUpdate, which is the easiest way to obtain virus definitions: These virus definitions are posted to the LiveUpdate servers once each week (usually on Wednesdays), unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, refer to the Virus Definitions (LiveUpdate).
  • Downloading the definitions using the Intelligent Updater: The Intelligent Updater virus definitions are posted on U.S. business days (Monday through Friday). You should download the definitions from the Symantec Security Response Web site and manually install them. To determine whether definitions for this threat are available by the Intelligent Updater, refer to the Virus Definitions (Intelligent Updater).

    The Intelligent Updater virus definitions are available: Read "How to update virus definition files using the Intelligent Updater" for detailed instructions.

3. To scan for and delete the infected files
  1. Start your Symantec antivirus program and make sure that it is configured to scan all the files.
  2. Run a full system scan.
  3. If any files are detected as infected with Backdoor.Berbew.E, click Delete.


    Note: If your Symantec antivirus product reports that it cannot delete an infected file, Windows may be using the file. To fix this, run the scan in Safe mode. For instructions, read the document, "How to start the computer in Safe Mode." Once you have restarted in Safe mode, run the scan again.

    When all the infected files have been deleted, restart the computer in Normal mode.


4. To reset the Internet Explorer home page
  1. Start Microsoft Internet Explorer.
  2. Connect to the Internet, and then go to the page that you want to set as your home page.
  3. Click the Tools menu > Internet Options.
  4. In the Home page section of the General tab, click Use Current, and then click OK.

For additional information, or if this procedure does not work, read the Microsoft® Knowledge Base article, "Home Page Setting Changes Unexpectedly, or You Cannot Change Your Home Page Setting, Article ID 320159 ."

5. To reset the Internet Explorer Search page
Follow the instructions for your version of Windows.

Windows 98/Me/2000
  1. Start Microsoft Internet Explorer.
  2. Click the Search button on the toolbar.
  3. In the Search pane, click Customize.
  4. Click Reset.
  5. Click Autosearch Settings.
  6. Select a search site from the drop-down list, and then click OK.
  7. Click OK.

Windows XP
Because Windows XP is set by default to use animated characters in the search, how you do this can vary. Read all the instructions before you start.
  1. Start Microsoft Internet Explorer.
  2. Click the Search button on the toolbar.
  3. Do one of the following:
    • If the pane that opens looks similar to this picture:





      click the word Customize, then skip to step h.

    • If the pane that opens has the words "Search Companion" at the top, and the center looks similar to this picture:





      click the "Change preferences" link as shown above. Proceed with step d.

  4. Click the "Change Internet search behavior" link.
  5. Under "Internet Search Behavior," click "With Classic Internet Search."
  6. Click OK. Then close Internet Explorer. (Close the program for the change to take effect.)
  7. Start Internet Explorer. When the search pane opens, it should now look similar to this:





    Click the word Customize, and then proceed with the next step.

  8. In the Search pane, click Customize.
  9. Click Reset.
  10. Click Autosearch Settings.
  11. Select a search site from the drop-down list, and then click OK.
  12. Click OK.
  13. Do one of the following:
    • If you were using (or want to continue using) the "Classic Internet Search" panel, stop here (or proceed with the next section).
    • If you want to go back to the "Search Companion" search (it usually has an animated character at the button), proceed with step n.

  14. Click the word Customize again.
  15. In the "Customize Search Settings" window, click "Use Search Companion," and then click OK.
  16. Close Internet Explorer. The next time you open it, it will again use the Search Companion.


6. To check other Internet Explorer settings.
This Trojan also makes several other changes to the registry, such as Web content zones. Because these are customizable, it is not possible for us to recommend what to change these to.

In Internet Explorer, these settings are accessed from Tools > Internet Options > Security tab.

If you are not sure what to change these to, you should reset each zone to the default setting by clicking the Default button.


Writeup By: Fergal Ladley